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Résumé

Abstract—Receiver-to-receiver time synchronization in wireless
networks is considered, and appropriate maximum-likelihood
estimators (MLE) for environments with exponential distrusted
reception delays are proposed. In the receiver-to-receiver synchronization
approach, time at receivers should be directly
related to one another without referring to the sender (reference),
which permits to eliminate the sender’s uncertainty from the
variable delays (time critical-path). The models and estimators
proposed for the sender-to-receiver approach are thus inappropriate
for the receiver-to-receiver one. A model that accurately
reflects the relative feature of the considered approach and
eliminates the senders’s uncertainty is used, where timestamps
at the receivers are directly related without referring to the
sender’s time or timestamps. By directly relating time at two
receivers with identical exponential reception delay, Exp(λ), it
yields a Laplace(0, 1/λ) distribution as the difference between
the two delays. By using the log-likelihood function of the latter
and the ML method, the offset estimator is analytically derived
and a linear program is given for the joint offset/skew model.
The accuracy of the proposed estimators has been numerically
analyzed by simulation. Results show high precision of the
proposed estimators, which can be integrated with any receiverto-
receiver synchronization protocol.